CAMBRIDGE, Mass. — As he strolled along the banks of the Charles River on Thursday evening, Durham Town Administrator Todd Selig saw nothing to indicate he was only a few blocks away from the two men at the center of an international manhunt.

Selig, who was attending a program at the Harvard Kennedy School of Government this week, spent Thursday evening in Cambridge with acquaintances from the program. He returned home between 10-11 p.m., taking a path along the river.

Unbeknownst to Selig, the two brothers suspected of planting a pair of bombs at the Boston Marathon earlier in the week may have been less than a mile away at the time.

Police say the suspects, 19-year-old Dzhokhar Tsarnaev and 26-year-old Tamerlan Tsarnaev, robbed a convenience store near the Massachusetts Institute of Technology campus at about 10:20 p.m., around the same time Selig was departing to head home. The pair then allegedly shot an MIT campus police officer and escaped in a stolen Mercedes SUV, taking the driver captive.

According to police, the driver either escaped or was released near a Shell gas station on Memorial Drive around 11 p.m.

Selig, who walked home along the river, would have passed within a few hundred feet of the Shell station. In an interview Friday morning, Selig said he was oblivious to the circumstances unfolding in Cambridge at the same time he was enjoying the company of his classmates.

“I didn't hear anything at that time,” he said. “I didn't notice anything at that time. I wasn't aware of it until earlier this morning.”

Police pursued the carjacked vehicle in Watertown, just west of Cambridge. Along the way, some kind of explosive devices were thrown from the vehicle in an apparent attempt to stop police. The carjackers and police then exchanged gunfire, leaving a transit police officer seriously injured.

Tamerlan Tsarnaev, who has been identified as Suspect No. 1 in the marathon bombings, was critically injured during the encounter and later pronounced dead. In the hours that followed, authorities launched a massive search for the other suspect, grinding the city of Boston and its suburbs to a halt.

After arriving in the area on Sunday, Selig has been staying at a university-owned apartment near the Harvard Business School. Like millions of others around the area, Selig was being asked to hunker down inside the building on Friday morning.

Selig said his wife contacted him in the morning and relayed the news that an emergency was underway in nearby Watertown. Selig said he could hear sirens blaring intermittently throughout the morning. A little after 6 a.m., a staff member knocked on his door to relay that classes had been postponed, then cancelled.

“We're safe, and there's not a soul outside,” he said shortly before 11 a.m. The streets are quiet. The main roads along the Charles River are quiet. There have been helicopters flying overhead slowly and a steady stream of sirens in the distance. The concern is — they've told us to not open the doors unless we can see who is there and we know who they are.”

Harvard administrators have been communicating with Selig and others throughout the day via email. The most recent message, which came at 11:44 a.m., reads: “With the seriousness of the situation in our area and the expanded search for the suspect, we again ask that you NOT leave the apartment building that you are in. Your safety is our first priority and we continue to work on your behalf and to keep you informed.”

Selig was participating this week in a program called “Mastering Negotiation, Building Agreements Across Boundaries.” He said the curriculum was focused on finding agreement and building bridges amid challenging conflict — an ironic juxtaposition, given the destruction unleashed in Boston this week.

“How sad,” Selig wrote in an email Friday. “How unfortunate. How pointless for our nation and the innocent victims. Locked down with emergency responder sirens clearly audible just blocks away since around 5 a.m., I choose to not lose hope. Our country is a truly great country. Such acts of terror serve only to strengthen the resolve of a free people and a free nation.”